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In this study, we developed an H 2 S gas sensor based on a MXene/MoS 2 heterostructure, using the Langmuir-Blodgett (LB) technique and chemical vapor deposition (CVD). Ti 3 C 2 T x MXene nanosheets were uniformly transferred onto SiO 2 /Si substrates via the LB technique, achieving near-complete coverage. Subsequently, flower-like MoS 2 was grown on the MXene-coated substrate through CVD, with vertical growth observed on the MXene layers. Our hybrid sensors exhibited a significant enhancement in gas response, with the MXene/MoS 2 heterostructure showing a response of 0.5 to H 2 S - approximately five times greater than that of pristine MXene. This improvement is attributed to the formation of a heterojunction, which increases electron mobility and reduces the depletion layer, enabling more efficient gas detection. Furthermore, the sensor demonstrated excellent selectivity for H 2 S over other gases, including H 2 , NO 2 , NH 3 , NO, and VOCs. The combination of the LB technique and CVD not only enhances gas sensor performance but also offers a promising strategy for synthesizing materials for various electrochemical applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Electromechanical metal oxides, such as piezoceramics, are often incompatible with soft polymers due to their crystallinity requirements, leading to high processing temperatures. This study explores the potential of ceria-based thin films as electromechanical actuators for flexible electronics. Oxygen-deficient fluorites, like cerium oxide, are centrosymmetric nonpiezoelectric crystalline metal oxides that demonstrate giant electrostriction. These films, deposited at low temperatures, integrate seamlessly with various soft substrates like polyimide and PET. Ceria thin films exhibit remarkable electrostriction ( M 33 > 10 -16 m 2 V -2 ) and inverse pseudo-piezo coefficients ( e 33 > 500 pmV -1 ), enabling large displacements in soft electromechanical systems. Our study explores resonant and off-resonant configurations in the low-frequency regime (<1 kHz), demonstrating versatility for three-dimensional and transparent electronics. This work advances the understanding of oxygen-defective metal oxide electromechanical properties and paves the way for developing versatile and efficient electromechanical systems for applications in biomedical devices, optical devices, and beyond.

The tunable properties of 2D transition-metal dichalcogenide (TMDs) materials are extensively investigated for high-performance and wavelength-tunable optoelectronic applications. However, the precise modification of large-scale systems for practical optoelectronic applications remains a challenge. In this study, a wafer-scale atomic assembly process to produce 2D multinary (binary, ternary, and quaternary) TMDs for broadband photodetection is demonstrated. The large-area growth of homogeneous MoS 2 , Ni 0.06 Mo 0.26 S 0.68 , and Ni 0.1 Mo 0.9 S 1.79 Se 0.21 is carried out using a succinct coating of the single-source precursor and subsequent thermal decomposition combined with thermal evaporation of the chalcogen powder. The optoelectrical properties of the multinary TMDs are dependent on the combination of heteroatoms. The maximum photoresponsivity of the MoS 2 -, Ni 0.06 Mo 0.26 S 0.68 -, and Ni 0.1 Mo 0.9 S 1.79 Se 0.21 -based photodetectors is 3.51 × 10 -4 , 1.48, and 0.9 A W -1 for 532 nm and 0.063, 0.42, and 1.4 A W -1 for 1064 nm, respectively. The devices exhibited excellent photoelectrical properties, which is highly beneficial for visible and near-infrared (NIR) photodetection., (© 2024 The Authors. Small published by Wiley‐VCH GmbH.)

Despite the advancement of the Internet of Things (IoT) and portable devices, the development of zero-biased sensing systems for the dual detection of light and gases remains a challenge. As an emerging technology, direct energy conversion driven by intriguing physical properties of two-dimensional (2D) materials can be realized in nanodevices or a zero-biased integrated system. In this study, we unprecedentedly attempted to exploit the photostimulated pyrothermoelectric coupling of two-dimensional SnSe for use in zero-biased multimodal transducers for the dual detection of light and gases. We synthesized homogeneous, large-area 6 in SnSe multilayers via a rational synthetic route based on the thermal decomposition of a solution-processed single-source precursor. Zero-biased SnSe transducers for the dual monitoring of light and gases were realized by exploiting the synergistic coupling of the photostimulated pyroelectric and thermoelectric effects of SnSe. The extracted photoresponsivity at 532 nm and NO 2 gas responsivity of the SnSe-based transducers corresponded to 1.07 × 10 -6 A/W and 13263.6% at 0 V, respectively. To bring universal applicability of the zero-biased SnSe transducers, the wide operation bandwidth photoelectrical properties (visible to NIR) and dynamic current responses toward two NO 2 /NH 3 gases were systematically evaluated.

This paper reports chemiresistive multiarray gas sensors through the synthesized ternary nanocomposites, using a one-pot method to integrate two-dimensional MXene (Ti 3 C 2 T x ) with Ti-doped WO 3 (Ti-WO 3 /Ti 3 C 2 T x ) and Ti 3 C 2 T x with Pd-doped SnO 2 (Pd-SnO 2 /Ti 3 C 2 T x ). The gas sensors based on Ti-WO 3 /Ti 3 C 2 T x and Pd-SnO 2 /Ti 3 C 2 T x exhibit exceptional sensitivity, particularly in detecting 70% at 1 ppm acetone and 91.1% at 1 ppm of H 2 S. Notably, our sensors demonstrate a remarkable sensing performance in the low-ppb range for acetone and H 2 S. Specifically, the Ti-WO 3 /Ti 3 C 2 T x sensor demonstrates a detection limit of 0.035 ppb for acetone, and the Pd-SnO 2 /Ti 3 C 2 T x sensor shows 0.116 ppb for H 2 S. Simultaneous measurements with Ti-WO 3 /Ti 3 C 2 T x - and Pd-SnO 2 /Ti 3 C 2 T x -based sensors enable the evaluation of both the concentration and type of unknown target gases, such as acetone or H 2 S. Furthermore, density functional theory calculations are performed to clarify the role of Ti and Pd doping in enhancing the performance of Ti-WO 3 /Ti 3 C 2 T x and Pd-SnO 2 /Ti 3 C 2 T x nanocomposites. Theoretical simulations contribute to a deeper understanding of the doping effects, providing essential insights into the mechanisms underlying the enhanced gas response of the gas sensors. Overall, this work provides valuable insights into the gas-sensing mechanisms and introduces a novel approach for high-performance multiarray gas sensing.

Constructing pertinent nanoarchitecture with abundant exposed active sites is a valid strategy for boosting photocatalytic hydrogen generation. However, the controllable approach of an ideal architecture comprising vertically standing transition metal chalcogenides (TMDs) nanosheets on a 3D graphene network remains challenging despite the potential for efficient photocatalytic hydrogen production. In this study, we fabricated edge-rich 3D structuring photocatalysts involving vertically grown TMDs nanosheets on a 3D porous graphene framework (referred to as 3D Gr). 2D TMDs (MoS 2 and WS 2 )/3D Gr heterostructures were produced by location-specific photon-pen writing and metal-organic chemical vapor deposition for maximum edge site exposure enabling efficient photocatalytic reactivity. Vertically aligned 2D Mo(W)S 2 /3D Gr heterostructures exhibited distinctly boosted hydrogen production because of the 3D Gr caused by synergetic impacts associated with the large specific surface area and improved density of exposed active sites in vertically standing Mo(W)S 2 . The heterostructure involving graphene and TMDs corroborates an optimum charge transport pathway to rapidly separate the photogenerated electron-hole pairs, allowing more electrons to contribute to the photocatalytic hydrogen generation reaction. Consequently, the size-tailored heterostructure showed a superior hydrogen generation rate of 6.51 mmol g -1 h -1 for MoS 2 /3D graphene and 7.26 mmol g -1 h -1 for WS 2 /3D graphene, respectively, which were 3.59 and 3.76 times greater than that of MoS 2 and WS 2 samples. This study offers a promising path for the potential of 3D structuring of vertical TMDs/graphene heterostructure with edge-rich nanosheets for photocatalytic applications.

Portable and personalized artificial intelligence (AI)-driven sensors mimicking human olfactory and gustatory systems have immense potential for the large-scale deployment and autonomous monitoring systems of Internet of Things (IoT) devices. In this study, an artificial Q-grader comprising surface-engineered zinc oxide (ZnO) thin films is developed as the artificial nose, tongue, and AI-based statistical data analysis as the artificial brain for identifying both aroma and flavor chemicals in coffee beans. A poly(vinylidene fluoride-co-hexafluoropropylene)/ZnO thin film transistor (TFT)-based liquid sensor is the artificial tongue, and an Au, Ag, or Pd nanoparticles/ZnO nanohybrid gas sensor is the artificial nose. In order to classify the flavor of coffee beans (acetic acid (sourness), ethyl butyrate and 2-furanmethanol (sweetness), caffeine (bitterness)) and the origin of coffee beans (Papua New Guinea, Brazil, Ethiopia, and Colombia-decaffeine), rational combination of TFT transfer and dynamic response curves capture the liquids and gases-dependent electrical transport behavior and principal component analysis (PCA)-assisted machine learning (ML) is implemented. A PCA-assisted ML model distinguished the four target flavors with >92% prediction accuracy. ML-based regression model predicts the flavor chemical concentrations with >99% accuracy. Also, the classification model successfully distinguished four different types of coffee-bean with 100% accuracy., (© 2024 The Authors. Advanced Science published by Wiley‐VCH GmbH.)

Atomic layer deposition (ALD) has become the most widely used thin-film deposition technique in various fields due to its unique advantages, such as self-terminating growth, precise thickness control, and excellent deposition quality. In the energy storage domain, ALD has shown great potential for supercapacitors (SCs) by enabling the construction and surface engineering of novel electrode materials. This review aims to present a comprehensive outlook on the development, achievements, and design of advanced electrodes involving the application of ALD for realizing high-performance SCs to date, as organized in several sections of this paper. Specifically, this review focuses on understanding the influence of ALD parameters on the electrochemical performance and discusses the ALD of nanostructured electrochemically active electrode materials on various templates for SCs. It examines the influence of ALD parameters on electrochemical performance and highlights ALD's role in passivating electrodes and creating 3D nanoarchitectures. The relationship between synthesis procedures and SC properties is analyzed to guide future research in preparing materials for various applications. Finally, it is concluded by suggesting the directions and scope of future research and development to further leverage the unique advantages of ALD for fabricating new materials and harness the unexplored opportunities in the fabrication of advanced-generation SCs., (© 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.)

The precisely tailored refractive index of optical materials is the key to utilizing and manipulating light during its propagation through the matrix, thereby improving their application performances. In this paper, mesoporous metal fluoride films with engineered composition (MgF 2 :LaF 3 ) are demonstrated to achieve finely tunable refractive indices. These films are prepared using a precursor-derived one-step assembly approach via the simple mixing of precursor solutions (Mg(CF 3 OO) 2 and La(CF 3 OO) 3 ); then pores are formed simultaneously during solidification owing to the inherent instability of La(CF 3 OO) 3 . The mesoporous structures are realized through Mg(CF 3 OO) 2 and La(CF 3 OO) 3 ions, which interacted with each other based on their electrostatic forces, providing a wide range of refractive indices (from 1.37 to 1.16 at 633 nm). Furthermore, it is systematically several MgF 2(1-x) -LaF 3(x) layers with different compositions (x = 0.0, 0.3, and 0.5) to form the graded refractive index coating that is optically consecutive between the substrate and the air for broadband and omnidirectional antireflection. An average transmittance of ≈98.03% (400-1100 nm) is achieved with a peak transmittance of ≈99.04% (at 571 nm), and the average antireflectivity is maintained at ≈15.75% even at an incidence of light of 65° (400-850 nm)., (© 2023 The Authors. Small published by Wiley-VCH GmbH.)

Despite the encouraging properties and research of 2D MoS 2 , an ongoing issue associated with the oxidative instability remains elusive for practical optoelectronic applications. Thus, in-depth understanding of the oxidation behavior of large-scale and homogeneous 2D MoS 2 is imperative. Here the structural and chemical transformations of large-area MoS 2 multilayers by air-annealing with altered temperature and time via combinatorial spectro-microscopic analyses (Raman spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy) are surveyed. The results gave indications pertaining to temperature- and time-dependent oxidation effects: i) heat-driven elimination of redundant residues, ii) internal strain stimulated by the formation of MoO bonds, iii) deterioration of the MoS 2 crystallinity, iv) layer thinning, and v) morphological transformation from 2D MoS 2 layers to particles. Photoelectrical characterization of the air-annealed MoS 2 is implemented to capture the link between the oxidation behavior of MoS 2 multilayers and their photoelectrical properties. The photocurrent based on MoS 2 air-annealed at 200 °C is assessed to be 4.92 µA, which is 1.73 times higher than that of pristine MoS 2 (2.84 µA). The diminution in the photocurrent of the photodetector based on MoS 2 air-annealed above 300 °C in terms of the structural, chemical, and electrical conversions induced by the oxidation process is further discussed., (© 2023 The Authors. Small Methods published by Wiley-VCH GmbH.)

This study suggests a Ru/ZnO bilayer grown using area-selective atomic layer deposition (AS-ALD) as a multifunctional layer for advanced Cu metallization. As a diffusion barrier and glue layer, ZnO is selectively grown on SiO 2 , excluding Cu, where Ru, as a liner and seed layer, is grown on both surfaces. Dodecanethiol (DDT) is used as an inhibitor for the AS-ALD of ZnO using diethylzinc and H 2 O at 120 °C. H 2 plasma treatment removes the DDT adsorbed on Cu, forming inhibitor-free surfaces. The ALD-Ru film is then successfully deposited at 220 °C using tricarbonyl(trimethylenemethane)ruthenium and O 2 . The Cu/bilayer/Si structural and electrical properties are investigated to determine the diffusion barrier performance of the bilayer film. Copper silicide is not formed without the conductivity degradation of the Cu/bilayer/Si structure, even after annealing at 700 °C. The effect of ZnO on the Ru/SiO 2 structure interfacial adhesion energy is investigated using a double-cantilever-beam test and is found to increase with ZnO between Ru and SiO 2 . Consequently, the Ru/ZnO bilayer can be a multifunctional layer for advanced Cu interconnects. Additionally, the formation of a bottomless barrier by eliminating ZnO on the via bottom, or Cu, is expected to decrease the via resistance for the ever-shrinking Cu lines., (© 2023 The Authors. Small published by Wiley-VCH GmbH.)

The recent introduction of alkali metal halide catalysts for chemical vapor deposition (CVD) of transition metal dichalcogenides (TMDs) has enabled remarkable two-dimensional (2D) growth. However, the process development and growth mechanism require further exploration to enhance the effects of salts and understand the principles. Herein, simultaneous predeposition of a metal source (MoO 3 ) and salt (NaCl) by thermal evaporation is adopted. As a result, remarkable growth behaviors such as promoted 2D growth, easy patterning, and potential diversity of target materials can be achieved. Step-by-step spectroscopy combined with morphological analyses reveals a reaction path for MoS 2 growth in which NaCl reacts separately with S and MoO 3 to form Na 2 SO 4 and Na 2 Mo 2 O 7 intermediates, respectively. These intermediates provide a favorable environment for 2D growth, including an enhanced source supply and liquid medium. Consequently, large grains of monolayer MoS 2 are formed by self-assembly, indicating the merging of small equilateral triangular grains on the liquid intermediates. This study is expected to serve as an ideal reference for understanding the principles of salt catalysis and evolution of CVD in the preparation of 2D TMDs., (© 2023 The Authors. Small published by Wiley-VCH GmbH.)

The rising importance of gas detection has prompted rigorous research on flexible and transparent high-performance gas sensors. We demonstrated a sensor for NO 2 detection at room temperature, in which our device was fabricated via screen printing on a flexible substrate, and MoS 2 and single-walled carbon nanotube (SWCNT) were coated on a specific area by the self-assembly method. This fabrication process is rapid, facile, and cost-effective. The proposed sensor enables precise and stable NO 2 gas sensing from 50 ppb to 100 ppm. This method should also be applicable to the selective detection of other gases., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A synthetic platform for industrially applicable two-dimensional (2D) semiconductors that addresses the paramount issues associated with large-scale production, wide-range photosensitive materials, and oxidative stability has not yet been developed. In this study, we attained the 6 in. scale production of 2D SnSe semiconductors with spatial homogeneity using a rational synthetic platform based on the thermal decomposition of solution-processed single-source precursors. The long-range structural and chemical homogeneities of the 2D SnSe layers are manifested using comprehensive spectroscopic analyses. Furthermore, the capability of the SnSe-based photodetectors for broadband photodetection is distinctly verified. The photoresponsivity and detectivity of the SnSe-based photodetectors are 5.89 A W -1 and 1.8 × 10 11 Jones at 532 nm, 1.2 A W -1 and 3.7 × 10 10 Jones at 1064 nm, and 0.14 A W -1 and 4.3 × 10 9 Jones at 1550 nm, respectively. The minimum rise times for the 532 and 1064 nm lasers are 62 and 374 μs, respectively. The photoelectrical analysis of the 5 × 5 SnSe-based photodetector array reveals 100% active devices with 95.06% photocurrent uniformity. We unequivocally validated that the air and thermal stabilities of the photocurrent yielded from the SnSe-based photodetector are determined to be >30 d in air and 160 °C, respectively, which are suitable for optoelectronic applications.

Ribosomes composed of genome-encoded heterogeneous rRNAs are implicated in the rapid adaptation of bacterial cells to environmental changes. A previous study showed that ribosomes bearing the most heterogeneous rRNAs expressed from the rrnI operon (I-ribosomes) are implicated in the preferential translation of a subset of mRNAs, including hspA and tpiA, in Vibrio vulnificus CMCP6. In this study, we show that HspA nascent peptides were predominantly bound to I-ribosomes. Specifically, I-ribosomes were enriched more than two-fold in ribosomes that were pulled down by immunoprecipitation of HspA peptides compared with the proportion of I-ribosomes in crude ribosomes and ribosomes pulled down by immunoprecipitation of RNA polymerase subunit β peptides in the wild-type (WT) and rrnI-completed strains. Other methods that utilized the incorporation of an affinity tag in 23S rRNA or chimeric rRNA tethering 16S and 23S rRNAs, which generated specialized functional ribosomes in Escherichia coli, did not result in functional I-ribosomes in V. vulnificus CMCP6. This study provides direct evidence of the preferential translation of hspA mRNA by I-ribosomes., (© 2022. Author(s).)

High-quality lead sulfide (PbS) films are deposited on selected substrate chemistries by an H 2 S-free metal-organic chemical vapor deposition (MOCVD) process using a single-source metal-organic complex (Pb(dmampS) 2 ). The complex is synthesized via a salt metathesis reaction between PbCl 2  and lithium 1-(dimethylamino)-2-methylpropane-2-thiolate (Li(dmampS)) in diethyl ether. Subsequent film deposition is conducted by a simple thermolysis process in the absence of H 2 S, yet chemical and structural analysis confirm chemically stoichiometric and homogenous films. Mechanistic studies with electron impact mass spectroscopy (EIMS) and gas chromatography mass spectroscopy (GCMS) suggest the selective cleavage of C-S bonds in the complex as the reason for the facile PbS formation with negligible impurity incorporation. The high crystallinity, low hole concentrations, and charge transport properties comparable and in many cases superior to films produced by atomic layer deposition (ALD) testify to the quality of the films. Lastly, rigid and flexible photodetectors fabricated with the PbS films exhibit considerably high photocurrents, reliable switching characteristics, and high sensitivity over a broad spectral bandwidth, highlighting the potential for realizing practical broadband photodetectors., (© 2022 The Authors. Small published by Wiley-VCH GmbH.)

The ribosome has long been thought to be a homogeneous cellular machine that constitutively and globally synthesises proteins from mRNA. However, recent studies have revealed that ribosomes are highly heterogeneous, dynamic macromolecular complexes with specialised roles in translational regulation in many organisms across the kingdoms. In this review, we summarise the current understanding of ribosome heterogeneity and the specialised functions of heterogeneous ribosomes. We also discuss specialised translation systems that utilise orthogonal ribosomes.

A challenge for chemiresistive-type gas sensors distinguishing mixture gases is that for highly accurate recognition, massive data processing acquired from various types of sensor configurations must be considered. The impact of data processing is indeed ineffective and time-consuming. Herein, we systemically investigate the effect of the selectivity for a target gas on the prediction accuracy of gas concentration via machine learning based on a support vector machine model. The selectivity factor S (X) of a gas sensor for a target gas "X" is introduced to reveal the correlation between the prediction accuracy and selectivity of gas sensors. The presented work suggests that (i) the strong correlation between the selectivity factor and prediction accuracy has a proportional relationship, (ii) the enhancement of the prediction accuracy of an elemental sensor with a low sensitivity factor can be attained by a complementary combination of the other sensor with a high selectivity factor, and (iii) it can also be boosted by combining the sensor having even a low selectivity factor., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

Herein, we reported a wearable photodetector based on hybrid nanocomposites, such as carbon materials and biocompatible semiconductor nanocrystals (NCs), exhibiting excellent photoresponsivity and superior durability. Currently, semiconductor nanocrystal quantum dots (QDs) containing heavy metals, such as lead or cadmium (in the form of lead sulfide (PbS) and cadmium sulfide (CdS)), are known to display excellent detection properties and are thus widely employed in the fabrication of photodetectors. However, the toxic properties of these heavy metals are well known. Hence, in spite of their enormous potential, the QDs based on these heavy metals are not generally preferred in biological or biomedical applications. These limitations, though, can be overcome by the judicious choice of alternate materials such as silver sulfide (Ag 2 S) NCs, which are biocompatible and exhibit multiple excitons in Ag 2 S QDs. The other chosen component is a carbon-based material, such as the multi-walled carbon nanotube (MWCNT), which is preferred primarily due to its strong and superior mechanical durability. In this study, a hybrid nanocomposite film was synthesized from Ag 2 S NCs and MWCNTs by a simple one-step fabrication process using ultrasonic irradiation. Additionally, this method did not involve any chemical functionalization or post-processing step. The size of Ag 2 S NCs in the hybrid film was controlled by the irradiation time and the power of the ultrasonic radiation. Further, appropriate composition ratio of the hybrid composite was optimized to balance the photo-response and mechanical durability of the photodetector. Thus, using this synthetic method, an excellent photoresponsivity property of the device was demonstrated for a near-infrared (NIR) light source with various light wavelengths. Furthermore, no visible change in photoresponsivity was observed for bending motions up to 10 5 cycles and for a range of angles (0-60°). This novel method provides an eco-friendly alternative to existing functional composites containing toxic heavy metals and is a promising approach for the development of wearable optoelectronic devices., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Organic polymer-based dielectrics with intrinsic mechanical flexibility and good processability are excellent candidates for the dielectric layer of flexible electronics. These polymer films can become even more rigid and electrically robust when modified through cross-linking processes. Moreover, the composites formed by dispersing nanoscale inorganic fillers in a polymer matrix can exhibit further improved polarization property. However, these strategies can be challenging as homogeneous dispersion of nanomaterials in the matrix is difficult to achieve; thus, degradation of electrically insulating properties of nanocomposite layers is often observed. Here, a high-k, pinhole-free, and flexible poly(vinyl alcohol) (PVA)-based nanocomposite dielectric is presented, incorporating 2D TiO 2 nanosheets (NSs) for the first time. Despite the attractive dielectric constant, exceptional flexibility, and electrically insulating property of PVA-TiO 2 nanocomposites, only few studies on these materials have been reported. The organic/inorganic nanosheet hybrid layer, which reaches an unprecedentedly high dielectric constant of 43.8 (more than four times higher than that of cross-linked PVA), also exhibits an outstanding leakage current density as low as 10 -9 A cm -2 . Furthermore, the repeated bending tests for nanocomposite capacitors reveal their capability of operating without any deterioration of their performances even after 1000 iterations of bending cycles at a bending radius of 3 mm., (© 2021 Wiley-VCH GmbH.)

Many research groups have been interested in the quartz crystal microbalance (QCM)-based gas sensors due to their superb sensitivity originated from direct mass sensing at the ng level. Despite such high sensitivities observed from QCM sensors, their ability to identify gas compounds still needs to be enhanced. Herein, we report a highly facile method that utilizes microcolumns integrated on a QCM gas-responsive system with enhanced chemical selectivity for sensing and ability to identify volatile organic compound single gases. Graphene oxide (GO) flakes are coated on the QCM electrode to substantially increase the adsorption of gas molecules, and periodic polydimethylsiloxane microcolumns with micrometer-scale width and height were installed on the GO-coated QCM electrode. The observed frequency shifts upon sensing of various single gas molecules (such as ethanol, acetone, hexane, etc.) can be analyzed accurately using a simple exponential model. The QCM sensor system with and without the microcolumn both exhibited high detection response values above 50 ng/cm 2 for sensing of the gases. Notably, the QCM sensor equipped with the microcolumn features gas identification ability, which is observed as distinct diverging behavior of time constants upon detection of different gases caused by the difference in diffusional transfer of molecules through the microcolumns. For example, the difference in the calculated time constant between ethanol and acetone increased from 22.6 to 92.1 s after installation of the microcolumn. This approach provides an easy and efficient method for identification of single gases, and it may be applied in various advanced sensor systems to enhance their gas selectivity.

The synthesis of organic-inorganic hybrid materials using individual metal-organic molecules as building blocks has been of interest for the last few decades. These hybrid materials are appealing due to the opportunities they provide with respect to a variety of potential applications. Here, we report a novel metal-organic nanostructure made by a hybrid synthetic process that is comprised of thermal evaporation (TE) and atomic layer deposition (ALD) for the metalation of an organic layer. In this work, 5,10,15,20-tetrakis(4-hydroxyphenyl)-21 H ,23 H -porphyrin ( p -(H 6 )THPP) and tin(ii) bis(trimethylsilyl)amide (Sn(btsa) 2 ) (or diethylzinc (DEZ)) were utilized as the main organic layer and ALD precursors, respectively. Sn and Zn atoms were coordinated sequentially via surface chemical reactions on specific functional groups of the p -(H 6 )THPP layer, which was deposited on a solid substrate. X-ray photoelectron spectroscopy (XPS) and UV-vis absorption spectroscopy were used to characterize and confirm the growth mechanism and optical properties of the synthesized hybrid films. This method should serve as a major breakthrough for building advanced organic-inorganic materials-based devices., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

To gain the target functionality of graphene for gas detection, nonfocused and large-scale compatible MeV electron beam irradiation on graphene with Ag patterns is innovatively adopted in air for chemical patterning of graphene. This strategy allows the metal-assisted site-specific oxidation of graphene to realize monolithically integrated graphene-chemically patterned graphene (CPG)-graphene homojunction-based gas sensors. The size-tunable CPG patterns can be mediated by regulating the size of Ag prepatterns. The impacts of highly energetic electron irradiation (HEEI) on graphene are summarized as follows: (i) the selective p-type doping and the defect generation of graphene by the HEEI-induced oxidation, (ii) the resistance of the homojunction devices manipulated by the HEEI dose, (iii) the band gap opening of graphene as well as the lowering of the Fermi level, (iv) the work function values for pristine graphene and CPG corresponding to 4.14 and 4.88 eV, respectively, and (v) graphene-CPG-graphene homojunction for NO 2 gas, revealing an 839% enhanced gas response compared with that of the pristine graphene-based gas sensor.

Perhydropolysilazane (PHPS), an inorganic polymer composed of Si-N and Si-H, has attracted much attention as a precursor for gate dielectrics of thin-film transistors (TFTs) due to its facile processing even at a relatively low temperature. However, an in-depth understanding of the tunable dielectric behavior of PHPS-derived dielectrics and their effects on TFT device performance is still lacking. In this study, the PHPS-derived dielectric films formed at different annealing temperatures have been used as the gate dielectric layer for solution-processed indium zinc oxide (IZO) TFTs. Notably, the IZO TFTs fabricated on PHPS annealed at 350 °C exhibit mobility as high as 118 cm 2 V -1 s -1 , which is about 50 times the IZO TFTs made on typical SiO 2 dielectrics. The outstanding electrical performance is possible because of the exceptional capacitance of PHPS-derived dielectric caused by the limited hydrolysis reaction of PHPS at a low processing temperature (<400 °C). According to our analysis, the exceptional dielectric behavior is originated from the electric double layer formed by mobile of protons in the low temperature-annealed PHPS dielectrics. Furthermore, proton conduction through the PHPS dielectric occurs through a three-dimensional pathway by a hopping mechanism, which allows uniform polarization of the dielectric even at room temperature, leading to amplified performance of the IZO TFTs.

Although energy-storage devices based on Li ions are considered as the most prominent candidates for immediate application in the near future, concerns with regard to their stability, safety, and environmental impact still remain. As a solution, the development of all-solid-state energy-storage devices with enhanced stability is proposed. A new eco-friendly polymer electrolyte has been synthesized by incorporating lithium trifluoromethanesulfonate into chemically modified methyl cellulose (LiTFS-LiSMC). The transparent and flexible electrolyte exhibits a good conductivity of near 1 mS cm -1 . An all-solid-state supercapacitor fabricated from 20 wt % LiTFS-LiSMC shows comparable specific capacitances to a standard liquid-electrolyte supercapacitor and an excellent stability even after 20 000 charge-discharge cycles. The electrolyte is also compatible with patterned carbon, which enables the simple fabrication of micro-supercapacitors. In addition, the LiTFS-LiSMC electrolyte can be recycled and reused more than 20 times with negligible change in its performance. Thus, it is a promising material for sustainable energy-storage devices., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Arrays of van der Waals gaps were manufactured by synthesizing the vertically aligned graphene layer stacked between two copper (Cu) catalytic films. The Cu-graphene-Cu laminated structure was obtained by directly synthesizing graphene on a patterned Cu film followed by depositing a second copper layer for optical measurements. The synthesis of graphene on the Cu surface was optimized by adjusting the synthesis temperatures and pre-annealing time using plasma enhanced chemical vapor deposition (PECVD). Resonant Raman spectroscopy measurements reveal that graphene can be synthesized on both bulk Cu foil and relatively thin Cu film under the same growth mechanism using PECVD. Structural and optical characterizations of the array of graphene van der Waals gaps were implemented by the transmission electron microscope and terahertz-time domain spectroscopy (THz-TDS). In THz-TDS, the measured THz amplitude transmitted through the graphene van der Waals gap slit array was constant regardless of the gap width determined by the number of graphene layers between the Cu thin films in a single slit. These results imply that the optical dielectric constant of graphene at THz frequencies in the out-of-plane direction is linearly proportional to the gap width. Our results of the manufacturing method can be adopted to investigate mechanical, electrical, and optical properties of other 2D materials such as h-BN, MoS 2 , and others. Furthermore, metal-graphene-metal structures with vertical orientations can be used in many electronic, optic, and optoelectronic applications.

The synthesis of low cost, high efficacy, and durable hydrogen evolution electrocatalysts from the non-noble metal group is a major challenge. Herein, we establish a simple and inexpensive chemical reduction method for producing molybdenum carbide (Mo 2 C) and tungsten carbide (W 2 C) nanoparticles that are efficient electrocatalysts in alkali and acid electrolytes for hydrogen evolution reactions (HER). Mo 2 C exhibits outstanding electrocatalytic behavior with an overpotential of -134 mV in acid medium and of -116 mV in alkaline medium, while W 2 C nanoparticles require an overpotential of -173 mV in acidic medium and -130 mV in alkaline medium to attain a current density of 10 mA cm -2 . The observed results prove the capability of high- and low-pH active electrocatalysts of Mo 2 C and W 2 C nanoparticles to be efficient systems for hydrogen production through HER water electrolysis., (Copyright © 2019 Hussain, Vikraman, Feroze, Song, An, Kim, Chun and Jung.)

Functional van der Waals heterojunctions of transition metal dichalcogenides are emerging as a potential candidate for the basis of next-generation logic devices and optoelectronics. However, the complexity of synthesis processes so far has delayed the successful integration of the heterostructure device array within a large scale, which is necessary for practical applications. Here, a direct synthesis method is introduced to fabricate an array of self-assembled WSe 2 /MoS 2 heterostructures through facile solution-based directional precipitation. By manipulating the internal convection flow (i.e., Marangoni flow) of the solution, the WSe 2 wires are selectively stacked over the MoS 2 wires at a specific angle, which enables the formation of parallel- and cross-aligned heterostructures. The realized WSe 2 /MoS 2 -based p-n heterojunction shows not only high rectification (ideality factor: 1.18) but also promising optoelectrical properties with a high responsivity of 5.39 A W -1 and response speed of 16 µs. As a feasible application, a WSe 2 /MoS 2 -based photodiode array (10 × 10) is demonstrated, which proves that the photosensing system can detect the position and intensity of an external light source. The solution-based growth of hierarchical structures with various alignments could offer a method for the further development of large-area electronic and optoelectronic applications., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Piezoelectric materials convert external mechanical force into electrical energy, due to the breaking of the centrosymmetry of the atomic structure. Piezoelectricity-based nano-generators (PNGs) based on two-dimensional transition metal dichalcogenides (TMDs) can generate electrical energy stably by the piezoelectric effect at their nanoscale thickness. However, the commercialization of TMD-based PNGs is limited by their poor piezoelectric performance and microscale energy harvesting. Here, we present the first centimeter-scale PNGs based on molybdenum disulfide (MoS 2 ) nanosheets with vertically grown hollow MoS 2 nanoflakes (v-MoS 2 NFs) obtained by chemical vapor deposition for energy harvesting from human motions. The collision of v-MoS 2 NFs with a preferred odd-atomic-layer number and their 2H antiparallel phase leads to efficient electrical energy generation during the bending movement. Further, basal MoS 2 films with v-MoS 2 NFs are transferred onto flexible substrates via conventional polymer-assisted methods for the fabrication of attachable and wearable piezoelectric power generators.

Despite many encouraging properties of transition metal dichalcogenides (TMDs), a central challenge in the realm of industrial applications based on TMD materials is to connect the large-scale synthesis and reproducible production of highly crystalline TMD materials. Here, the primary aim is to resolve simultaneously the two inversely related issues through the synthesis of MoS 2(1- x ) Se 2 x ternary alloys with customizable bichalcogen atomic (S and Se) ratio via atomic-level substitution combined with a solution-based large-area compatible approach. The relative concentration of bichalcogen atoms in the 2D alloy can be effectively modulated by altering the selenization temperature, resulting in 4 in. scale production of MoS 1.62 Se 0.38 , MoS 1.37 Se 0.63 , MoS 1.15 Se 0.85 , and MoS 0.46 Se 1.54 alloys, as well as MoS 2 and MoSe 2 . Comprehensive spectroscopic evaluations for vertical and lateral homogeneity in terms of heteroatom distribution in the large-scale 2D TMD alloys are implemented. Se-stimulated strain effects and a detailed mechanism for the Se substitution in the MoS 2 crystal are further explored. Finally, the capability of the 2D alloy for industrial application in nanophotonic devices and hydrogen evolution reaction (HER) catalysts is validated. Substantial enhancements in the optoelectronic and HER performances of the 2D ternary alloy compared with those of its binary counterparts, including pure-phase MoS 2 and MoSe 2 , are unambiguously achieved., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Low-dimensional nanostructures and their complementary hybridization techniques are in the vanguard of technological advances for applications in transparent and flexible nanoelectronics due to the intriguing electrical properties related to their atomic structure. In this study, we demonstrated that welding of Ag nanowires (NWs) encapsulated in graphene was stimulated by flux-optimized, high-energy electron beam irradiation (HEBI) under ambient conditions. This methodology can inhibit the oxidation of Ag NWs which is induced by the inevitably generated reactive ozone as well as improve of their electrical conductivity. We have systematically explored the effects of HEBI on Ag NWs and graphene. The optimized flux for HEBI welding of the Ag NWs with graphene was 150 kGy, which decreased the sheet resistance of the graphene/Ag NWs to 12 Ohm/sq. Following encapsulation with graphene, the initial chemical states of the Ag NWs were well-preserved after flux-tuned HEBI, whereas graphene underwent local HEBI-induced defect generation near the junction area. We further employed resonant Raman spectroscopy to follow the structural evolution of the sacrificial graphene in the hybrid film after HEBI. Notably, the sheet resistance of the welded Ag NWs encapsulated with graphene after HEBI was well-maintained even after 85 days.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) such as molybdenum disulfide (MoS 2 ) and tungsten diselenide (WSe 2 ), have recently attracted attention for their applicability as building blocks for fabricating advanced functional materials. In this study, a high quality hybrid material based on 2D TMD nanosheets and ZnO nanopatches was demonstrated. An organic promoter layer was employed for the large-scale growth of the TMD sheet, and atomic layer deposition (ALD) was utilized for the growth of ZnO nanopatches. Photodetectors based on 2D TMD nanosheets and ZnO nanopatches were successfully fabricated and investigated, which showed a high photoresponsivity of 2.7 A/W. Our novel approach is a promising and effective method for the fabrication of photodetectors with a new structure for application in TMD-based transparent and flexible optoelectronic devices., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Here, we present a new approach to dual-channel gas sensors on the basis of a role-allocated graphene/ZnO heterostructure, formed by the complementary hybridization of graphene and a ZnO thin film. The method enables cyclic and reproducible gas response as well as high gas response. The role allocation of graphene and ZnO was verified by studying the electrical transport properties of the heterostructure. The results indicated that the ZnO top layer and graphene bottom layer act as a gas adsorption layer and a carrier conducting layer, respectively. The charge interactions of the heterostructures were systematically explored by monitoring changes in transfer characteristics at room temperature and elevated temperature ( T = 250 °C) after introducing 20 ppm NO 2 . These results can be understood in terms of the dual-channel effect of the graphene/ZnO heterostructures. Remarkably, an abrupt and reliable gas response under periodic NO 2 gas injection was unambiguously achieved by the heterostructure-based gas sensors and as ∼30 times higher than those of a graphene-based gas sensor. These proposed heterostructures represent a fundamental building block of a complementary hybrid gas sensor with highly sensitive and reproducible gas response.

It is generally assumed that each organism has evolved to possess a unique ribosomal RNA (rRNA) species optimal for its physiological needs. However, some organisms express divergent rRNAs, the functional roles of which remain unknown. Here, we show that ribosomes containing the most variable rRNAs, encoded by the rrnI operon (herein designated as I-ribosomes), direct the preferential translation of a subset of mRNAs in Vibrio vulnificus, enabling the rapid adaptation of bacteria to temperature and nutrient shifts. In addition, genetic and functional analyses of I-ribosomes and target mRNAs suggest that both I-ribosomal subunits are required for the preferential translation of specific mRNAs, the Shine-Dalgarno sequences of which do not play a critical role in I-ribosome binding. This study identifies genome-encoded divergent rRNAs as regulators of gene expression at the ribosome level, providing an additional level of regulation of gene expression in bacteria in response to environmental changes.

Single source precursors for coating and subsequent thermal decomposition processes enable a large-scale, low-cost synthesis of two-dimensional transition metal dichalcogenides (TMDs). However, practical applications based on two-dimensional TMDs have been limited by the lack of applicable single source precursors for the synthesis of p-type TMDs including layered tungsten diselenide (WSe 2 ). We firstly demonstrate the simple and facile synthesis of WSe 2 layers using a newly developed precursor that allows improved dispersibility and lower decomposition temperature. We study the thermal decomposition mechanism of three types of (Cat + ) 2 [WSe 4 ] precursors to assess the most suitable precursor for the synthesis of WSe 2 layers. The resulting chemical and structural exploration of solution-processed WSe 2 layers suggests that the (CTA) 2 [WSe 4 ] may be a promising precursor because it resulted in the formation of high-crystalline WSe 2 . In addition, this study verifies the capability of WSe 2 layers for multifunctional applications in optoelectronic and electronic devices. The photocurrent of WSe 2 -based photodetectors shows an abrupt switching behavior under periodic illumination of visible or IR light. The extracted photoresponsivity values for WSe 2 -based photodetectors recorded at 0.5 V correspond to 26.3 mA W -1 for visible light and 5.4 mA W -1 for IR light. The WSe 2 -based field effect transistors exhibit unipolar p-channel transistor behavior with a carrier mobility of 0.45 cm 2 V -1 s -1 and an on-off ratio of ∼10., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

To find an effective alternative to scarce, high-cost noble platinum (Pt) electrocatalyst for hydrogen evolution reaction (HER), researchers are pursuing inexpensive and highly efficient materials as an electrocatalyst for large scale practical application. Layered transition metal dichalcogenides (TMDCs) are promising candidates for durable HER catalysts due to their cost-effective, highly active edges and Earth-abundant elements to replace Pt electrocatalysts. Herein, we design an active, stable earth-abundant TMDCs based catalyst, WS (1- x ) Se x nanoparticles-decorated onto a 3D porous graphene/Ni foam. The WS (1- x ) Se x /graphene/NF catalyst exhibits fast hydrogen evolution kinetics with a moderate overpotential of ~-93 mV to drive a current density of 10 mA cm -2 , a small Tafel slope of ~51 mV dec -1 , and a long cycling lifespan more than 20 h in 0.5 M sulfuric acid, which is much better than WS₂/NF and WS₂/graphene/NF catalysts. Our outcomes enabled a way to utilize the TMDCs decorated graphene and precious-metal-free electrocatalyst as mechanically robust and electrically conductive catalyst materials.

Here, we report the synthesis of a vertical MoSe 2 /WSe 2 p-n heterostructure using a sputtering-CVD method. Unlike the conventional CVD method, this method produced a continuous MoSe 2 /WSe 2 p-n heterostructure. WSe 2 and MoSe 2 back-gated field effect transistors (FETs) exhibited good gate modulation behavior, and high hole and electron mobilities of ∼2.2 and ∼15.1 cm 2 V -1 s -1 , respectively. The fabricated vertical MoSe 2 /WSe 2 p-n diode showed rectifying I - V behavior with back-gate tunability. The rectification ratio of the diode was increased with increasing gate voltage, and was increased from ∼18 to ∼1600 as the gate bias increased from -40 V to +40 V. This is attributed to the fact that the barrier height between p-WSe 2 and n-MoSe 2 is modulated due to the back-gate bias. The rectification ratio is higher than the previously reported values for the TMDC p-n heterostructure grown by CVD., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Herein, we report on an unprecedented synthetic method for single-layered GO that takes just a few tens of minutes. This rationally designed solid-state oxidation based on alkali metal carbonates (Li2CO3, Na2CO3, K2CO3) involves a molten salt reaction, which enables the effective exfoliation and oxidation of graphene layers without using H2SO4 and KMnO4. The advantage of this approach is not only the ability to avoid the introduction of strong acid reactants in the reaction process, but this approach also leads to a 4.2 times larger specific surface area than conventional GO. For these reasons, we anticipate that this green, safe, fast and effective approach enables practical applications in graphene-based energy storage and light-absorbing black materials.

Highly sensitive and wearable chemical sensors for the detection of toxic gas molecules are given significant attention for a variety of applications in human health care and environmental safety. Herein, we demonstrated fiber-type gas sensors based on graphene oxide functionalized with organic molecules such as heptafluorobutylamine (HFBA), 1-(2-methoxyphenyl)piperazine (MPP), and 4-(2-keto-1-benzimidazolinyl)piperidine (KBIP) by assembling functionalized graphene oxide (FGO) on a single yarn fabric. These gas sensors of FGO on yarn exhibited extraordinarily higher sensitivity upon exposure to gas molecules than chemically reduced graphene oxide due to many active functional groups on the GO surface. Furthermore, the mechanical stability and chemical durability of the resulting gas sensors are well-maintained. Based on these results, we expected that our sensors with high sensitive and wearability will provide a good premise for wearable chemical sensors-based multidisciplinary applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A facile methodology for the large-scale production of layer-controlled MoS 2 layers on an inexpensive substrate involving a simple coating of single source precursor with subsequent roll-to-roll-based thermal decomposition is developed. The resulting 50 cm long MoS 2 layers synthesized on Ni foils possess excellent long-range uniformity and optimum stoichiometry. Moreover, this methodology is promising because it enables simple control of the number of MoS 2 layers by simply adjusting the concentration of (NH 4 ) 2 MoS 4 . Additionally, the capability of the MoS 2 for practical applications in electronic/optoelectronic devices and catalysts for hydrogen evolution reaction is verified. The MoS 2 -based field effect transistors exhibit unipolar n-channel transistor behavior with electron mobility of 0.6 cm 2 V -1 s -1 and an on-off ratio of ≈10³. The MoS 2 -based visible-light photodetectors are fabricated in order to evaluate their photoelectrical properties, obtaining an 100% yield for active devices with significant photocurrents and extracted photoresponsivity of ≈22 mA W -1 . Moreover, the MoS 2 layers on Ni foils exhibit applicable catalytic activity with observed overpotential of ≈165 mV and a Tafel slope of 133 mV dec -1 . Based on these results, it is envisaged that the cost-effective methodology will trigger actual industrial applications, as well as novel research related to 2D semiconductor-based multifaceted applications., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Wearable strain-pressure sensors for detecting electrical signals generated by human activities are being widely investigated because of their diverse potential applications, from observing human motion to health monitoring. In this study, we fabricated reduced graphene oxide (rGO)/single-wall carbon nanotube (SWCNT) hybrid fabric-based strain-pressure sensors using a simple solution process. The structural and chemical properties of the rGO/SWCNT fabrics were characterized using scanning electron microscopy (SEM), Raman, and X-ray photoelectron spectroscopy (XPS). Complex networks containing rGO and SWCNTs were homogeneously formed on the cotton fabric. The sensing performance of the devices was evaluated by measuring the effects of bending strain and pressure. When the CNT content was increased, the change in relative resistance decreased, while durability was significantly improved. The rGO/SWCNT (0.04 wt %) fabric sensor showed particularly high mechanical stability and flexibility during 100 000 bending tests at the extremely small bending radius of 3.5 mm (11.6% bending strain). Moreover, the rGO/SWCNT fabric device exhibited excellent water resistant properties after 10 washing tests due to its hydrophobic nature. Finally, we demonstrated a fabric-sensor-based motion glove and confirmed its practical applicability.

A cost effective and efficient alternative counter electrode (CE) to replace commercially existing platinum (Pt)-based CEs for dye-sensitized solar cells (DSSCs) is necessary to make DSSCs competitive. Herein, we report the large-area growth of molybdenum telluride (MoTe 2 ) thin films by sputtering-chemical vapor deposition (CVD) on conductive glass substrates for Pt-free CEs of DSSCs. Cyclic voltammetry (CV), Tafel curve analysis, and electrochemical impedance spectroscopy (EIS) results showed that the as-synthesized MoTe 2 exhibited good electrocatalytic properties and a low charge transfer resistance at the electrolyte-electrode interface. The optimized MoTe 2 CE revealed a high power conversion efficiency of 7.25% under a simulated solar illumination of 100 mW cm -2 (AM 1.5), which was comparable to the 8.15% observed for a DSSC with a Pt CE. The low cost and good electrocatalytic properties of MoTe 2 thin films make them as an alternative CE for DSSCs.

A novel three-dimensional transition metal dichalcogenide (TMD) structure consisting of seamless hollow nanoflakes on two-dimensional basal layers was synthesized by a one-step chemical vapor deposition method. Here, we demonstrate that the as-grown nanoflakes are formed on an organic promoter layer which served as a positive template and are swollen at the grain boundaries by the bubbling effect. TMD nanosheets with hollow nanoflakes are successfully applied as chemical sensors, and it was found that their gas adsorption property is strongly related to the internal strain gradient resulting from the variation in the lattice parameter. This result is consistent with the theoretical prediction in previous studies. Our chemical vapor deposition-based approach is an efficient way to generate TMD-based nanostructures over a large surface area for various practical applications such as chemical sensors.

Complementary combination of heterostructures is a crucial factor for the development of 2D materials-based optoelectronic devices. Herein, an appropriate solution for fabricating complementary dimensional-hybrid nanostructures comprising structurally tailored ZnO nanostructures and 2D materials such as graphene and MoS 2 is suggested. Structural features of ZnO nanostructures hydrothermally grown on graphene and MoS 2 are deliberately manipulated by adjusting the pH value of the growing solution, which will result in the formation of ZnO nanowires, nanostars, and nanoflowers. The detailed growth mechanism is further explored for the structurally tailored ZnO nanostructures on the 2D materials. Furthermore, a UV photodetector based on the dimensional-hybrid nanostructures is fabricated, which demonstrates their excellent photocurrent and mechanical durability. This can be understood by the existence of oxygen vacancies and oxygen-vacancies-induced band narrowing in the ZnO nanostructures, which is a decisive factor for determining their photoelectrical properties in the hybrid system.

New fiber-type piezoelectric nanogenerator devices consisting of radially aligned perovskite PbTiO 3 nanotubes are designed for energy harvesting from arbitrary mechanical motion. The free-standing fiber-type nanogenerators generate constant amount of electric power by bending or wind motion regardless of direction, thus, extending the possibility of their practical applications., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

RraA is a protein inhibitor of RNase E, which degrades and processes numerous RNAs in Escherichia coli. Streptomyces coelicolor also contains homologs of RNase E and RraA, RNase ES and RraAS1/RraAS2, respectively. Here, we report that, unlike other RraA homologs, RraAS1 directly interacts with the catalytic domain of RNase ES to exert its inhibitory effect. We further show that rraAS1 gene deletion in S. coelicolor results in a higher growth rate and increased production of actinorhodin and undecylprodigiosin, compared with the wild-type strain, suggesting that RraAS1-mediated regulation of RNase ES activity contributes to modulating the cellular physiology of S. coelicolor.

A comprehensive study for the effect of interfacial buffer layers on the electrical transport behavior in CVD-grown graphene based devices has been performed by ac-impedance spectroscopy (IS) analysis. We examine the effects of the trap charges at graphene/SiO 2 interface on the total capacitance by introducing self-assembled monolayers (SAMs). Furthermore, the charge transports in the polycrystalline graphene are characterized through the temperature-dependent IS measurement, which can be explained by the potential barrier model. The frequency-dependent conduction reveals that the conductivity of graphene is related with the mobility, which is limited by the scattering caused by charged adsorbates on SiO 2 surface.